Difference Between Stainless Steel Seamless Pipe And Welded Pipe

Stainless steel has good comprehensive performance and good appearance surface characteristics, and is widely used in all walks of life. Similarly, stainless steel pipes are no exception. Stainless steel pipes are a type of steel with a hollow cross-section, generally divided into seamless steel pipe and welded steel pipe. There are also certain differences in their processing methods and performance, as follows:

Differences in manufacturing process

Stainless steel seamless pipes use round tube billets as raw materials for perforation, and are made through cold rolling, cold drawing or hot extrusion production processes. There are no welding points on the pipes; welded pipes are made of steel plates or steel strips after being curled and formed by the unit and the mold, and the inner wall of the pipe generally has a weld.

Differences in the appearance of steel pipes

Stainless steel seamless pipes have low steel pipe precision, uneven wall thickness, low brightness of the inner and outer surfaces of the pipe, high sizing cost, and pitting and black spots on the inner and outer surfaces that are difficult to remove. Therefore, the walls of seamless pipes usually produced are thicker.

The tolerance of the wall thickness of the welded pipe is very small, and the wall thickness of the entire circumference is very uniform; the steel pipe has high precision, the inner and outer surfaces of the pipe are bright, and can be arbitrarily sized; it can be made into thin-walled pipes.

Differences in performance and price

Stainless steel seamless pipes are usually superior to welded pipes in terms of corrosion resistance, pressure bearing and high temperature resistance. It can withstand higher pressures and temperatures, and is very suitable for fluid transportation applications that require high strength and high temperature resistance. Due to the improvement of production processes, the mechanical properties and mechanical properties of welded pipes are gradually approaching those of seamless pipes, but the price is usually more economical and suitable for low pressure or applications that do not require extremely high strength.

Features of stainless steel seamless pipes

1. Advantages

High strength: Seamless steel pipes have superior performance under high pressure and high temperature, and are suitable for harsh industrial environments.

Forming diversity: It can be made into a variety of cross-section forms to flexibly respond to the needs of different use conditions.

Improved mechanical properties: After cold rolling or hot rolling, the grain of the seamless steel pipe is refined, the mechanical properties are significantly improved, and it has better wear resistance and corrosion resistance.

2. Disadvantages

Uneven wall thickness: Uneven wall thickness of steel pipes is common during cold rolling, and some pipes may have residual stress and surface defects as they cool.

Poor surface finish: There may be traces on the inner surface of the steel pipe, which are not easy to remove, affecting the appearance and fluidity of the fluid in the pipe.

Features of stainless steel welded steel pipes

1. Advantages

Uniform wall thickness: The wall thickness of welded steel pipes is relatively uniform, which can maintain high production accuracy and is suitable for large-scale industrial applications.

Low residual stress: After bright annealing treatment, the residual stress of welded steel pipes is effectively eliminated, and the stability of the pipe is relatively high.

Lower production cost: Compared with seamless steel pipes, the production process of welded steel pipes is simpler, the price is more economical, and it is suitable for mass production.

2. Disadvantages

The existence of weld seams: There are weld seams inside the welded steel pipe. Although it has been treated at high temperature, the weld seams may still affect the strength of the pipe, especially under high pressure.

Weak pressure resistance: Compared with seamless steel pipes, welded steel pipes have poor corrosion resistance and pressure bearing performance, and cannot meet the needs of some harsh environments.

Based on the features and differences between stainless steel seamless pipes and welded pipes, reasonable selection should be made when applying to achieve economic, beautiful and reliable effects:

1. When making decorative pipes, product pipes, and prop pipes, good surface effects are generally required, and stainless steel welded pipes are usually selected.

2. For generally low-pressure fluid transportation, such as transportation of water, oil, gas, air, and low-pressure systems such as heating hot water or steam, stainless steel welded pipes are usually selected.

3. For pipelines used to transport fluids in industrial engineering and large equipment, as well as pipelines for transporting fluids that require high temperature, high pressure, and high strength on boilers in power plants and nuclear power plants, stainless steel seamless pipes should be selected.

4. Stainless steel welded pipes are generally used for liquid transportation below 0.8MPa, and seamless pipes can be used to withstand liquid transportation above 0.8MPa. If the pressure requirement is not high, it will be more economical to use welded pipes.